A UK trial of dronabinol (delta-9-THC) in 498 patients did not slow the progression of multiple sclerosis (MS) compared to placebo. Critics will point out that this is only one of many cannabinoids found in marijuana; and that the placebo arm did better than expected (thus limiting the ability to detect the effects of the drug). Nonetheless, the result is the strongest argument yet against the neuroprotective effects of THC in MS population.

New trials in progressive MS are coming

Later this year, two trials will open for people with progressive MS. The first, called MS-SMART, will be conducted in the United Kingdom, and the second, SPRINT-MS, in the United States. Both trials will look into the effects of Ibudilast, an oral anti-inflammatory medication, in people with primary progressive and secondary progressive MS.